Both versions completely smooth on my system, both windowed and full-screen. (They better be at 100% CPU usage just to move a single object :) ).
AMD Athlon XP 3000+ with 1 gig RAM, 128 meg ATI Radeon 9600 Pro, XP Pro SP2, DX 9.0c
AMD Athlon XP 3000+ with 1 gig RAM, 128 meg ATI Radeon 9600 Pro, XP Pro SP2, DX 9.0c